Process of inhibiting deposition of organic substances in heat exchangers and the like operating at elevated temperatures



Unit d ates.,.

tenet Patented Oct. 13, 1959 2,908,624 PROCESS, OF :mnmrrnso nErosrnoNOF OR- GANIC SUBSTANCES IN HEAT EXCHANGERS AND THE ,LIKE OPERATING ATELEVATED TEMPERATURES Carl E. Johnson, Westchester, and William H.Thompson, Downers Grove, 111., assignors to National AluminateCorporation, Chicago, 111., a corporation of Delaware ApplicationDecember 2, 1955 Serial No. 550,750

5 Claims. 01. 20848) No Drawing.

"fete 5 hydrocarbon liquid, a salt of an organic aliphatic diditions ofhigh temperatures whereby said liquids tend to a form deposits on suchmetal surfaces.

In the processing of hydrocarbon liquids, particularly petroleumhydrocarbon liquids, elevated temperatures are often used in manynecessary and important production operations. To handle liquids atelevated temperatures heat exchangers and like devices are oftenemployed to control the heat transfer rate from one operational step toanother. When hydrocarbon liquids contact hot metal surfaces there issometimes a tendency for deposits by petroleum hydrocarbon liquids incontact with heat transfer equipment.

Yet another object is to furnish a chemical treatment capable of beingcombined with a thermally unstable, deposit-forming liquid whereby saidliquid will not form deposits upon metal surfaces at elevatedtemperatures.

Still another object is to provide a chemical treatment which willremove high temperature carbonaceous deposits from metal surfaces ofpetroleum refining equipment'without the necessity of stopping theoperations of such equipment. Other objects will appear hereinafter.

In accomplishing these objects in accordance with the invention it hasbeen found that new and improved results in inhibiting the formation oforganic deposits from petroleum hydrocarbon liquids during theprocessing thereof at elevated temperatures, particularly attemperatures within the range of about 225 9 F. to 800 F., are obtainedby adding, preferably by dissolving in the carboxylic acid containing atleast 10 carbon atoms in a hydrocarbon structure and a glyoxalidinewherein the carbon atom in the 2-position is linked to a higher alitheliquid to decompose or undergo a chemical reaction that manifests itselfin the form of deposits. These deposits may be either coke-like or theymay be in the form of tenacious, soft, sticky sludges. In the firstinstance, the deposits may be considered as pyrolyzed decompositionproducts whereas in the second type they may be considered as oxidationproducts and/or'polymerizate compositions.

In either of the above cases the deposits tendto materially decrease theheat treansfer capacities of the metal surfaces and hence increaseoperating expense'silf These deposits also require additional effort andtime'to remove and to restore the equipment to its. original operatingefiiciency.

Petroleum refinery operations often encounter the above describedconditions in many stages in the refining process. These deposits formon heat transfer surfaces at temperatures as low as'about 225 F. and maybe evidenced at temperatures as extreme as 800 F.

It is nearly impossible to preNent these deposits by coating the metalsurfaces with a protective permanent coating due to the possible loss ofheat transfer. Also a problem in treating metal surfaces in petroleumprocessing to prevent high temperature organic deposits is the largevolume of liquid that contacts such equipment.

It would be advantageous if a chemical treatmentcould be added in anextremely small amount to a. hydrocarbon liquid which tends to form hightemperature deposits whereby such deposits would be prevented. It wouldalso be desirable if such a chemical would not only prevent suchdeposits but would also remove them without necessitating the stoppageof a given operation. It therefore becomes an object of the presentinvention to prevent the formation of high temperature carbonaceousdeposits on metal surfaces by chemical means.

Another object is to furnish a chemical which when added to ahydrocarbon liquid will prevent the depositforming tendencies of saidliquid when it contacts metal surfaces at elevated temperatures.

A further object is to provide a chemical treatment which will prevent,the formationof high temperature phatic hydrocarbon group containing atleast 8 carbon atoms, the carbon atom in the 4-position is linked to amember from the group consisting of hydrogen and lower aliphatichydrocarbon groups containing not more than 6carbon atoms, the carbonatom in the 5-position is linked to a member from the group consistingof hydrogen and lower aliphatic hydrocarbon groups containing not morethan 6 carbon atoms, there being at least one hydrogen atom on each ofthe carbon atoms in the 4- and 5-positions, and the nitrogen atom in thel-position islinked to a member from the group consisting of hydrogenand lower aliphatic groups containing not more than 6 carbon atoms, saidlast named lower aliphatic groups being composed of atoms from the groupconsisting of hydrogen, carbon, nitrogen and oxygen.

These compounds can also be characterized as monoglyoxalidine salts ofsaid organic aliphatic dicarboxylic acids or diglyoxalidine salts of'such acids, depending .upon whether one or two mols of the glyoxalidineis reacted with the organic aliphatic dicarboxylic acid. If only one molof the plyoxalidine is reacted the resultant compound is a monoaminesalt containing a free carboxylic acid group. If two mols of theglyoxalidine are reacted the resultant compound is a diamine salt. Theglyoxalidines employed as starting materials are made by well knownprocedures by reacting a fatty acid with an aliphatic polyamine with theelimination of water as described, for example, in Wilson, U.S. Patent2,267,965 and Wilkes et al. U.S. Patent 2,268,273.

The glyoxalidines with which the present invention is particularlyconcerned are those in which the glyoxalidine portion of the molecule isderived by reacting together. "one of the acids from the groupconsisting of lauric acid, myristic acid, palmitic acid, oleic acid andstearic acid, with an aliphatic polyamine from the group consisting ofaminoethylethanolamine, diethylenetriamine and 'triethylene tetramine.When the glyoxalidine is de rived from aminoethylethanolamine theresultant product contains a hydroxyethyl group on the 1-position. Whenthe glyoxalidine is derived from diethylenetriamine the will contain 11carbon atoms. If the glyoxalidine is made from oleic acid thehydrocarbon group in the 2position will be a heptadecenyl groupcontaining 17 carbon atoms. The hydrocarbon group in the 2-positionpreferably contains 13 to 17 carbon atoms for the purpose of the presentinvention.

Specific examples of glyoxalidines that can be reacted with sebacicacid, dilinoleic acid and other long chain organic aliphaticdicarboxylic acids in preparing salts suitable for the purpose of theinvention are: 1-(2-hydroxyethyl)-2-undecyl glyoxalidine,1-(2hydroxyethyl)- 2-tridecyl glyoxalidine,1-(2-hydroxyethyl)-2-pentadecyl glyoxalidine,1-(Z-hydroxyethyl)-2-heptadecyl glyoxalidine,1-(2-hydroxyethyl)-2-heptadecenyl glyoxalidine, 1- 2-amin0ethyl)-2-undecyl glyoxalidine, 1-(2-aminoethyl)- 2-tridecyl glyoxalidine,1-(2-aminoethyl)-2-pentadecyl glyoxalidine,1-(2-aminoethyl)-2-heptadecyl glyoxalidine,1-(2-aminoethyl)-2-hepta,decenyl glyoxalidine, 1-[(2-aminoethyl)-aminoethyl]-2-undecyl glyoxalidine, 1-[(2-aminoethyl)-aminoethyl]-2-tridecyl glyoxalidine, 1-[(2- aminoethyl)arninoethyl]-2-pentadecyl glyoxalidine, 1- Z-aminoethyl) -aminoethyl]-2-heptadecyl glyoxalidine, 1-[ (Z-aminoethyl-aminoethyl]-2-heptadecenyl glyoxalidine, 4-methyl-2-undecyl glyoxalidine,4-methyl-2-tridecyl glyoxalidine, 4-methyl-2-pentadecyl glyoxalidine, 4-methyl-Z-heptadecyl glyoxalidine, 4-methyl-2-heptadecenyl glyoxalidine.

The organic aliphatic dicarboxyl ic acid salts are prepared by mixing aglyoxalidine of the types described and an organic aliphaticdicarboxylic acid of the type described in mol ratios of 1:1 in case itis desired to prepare the monoamine salt, or 2:1 in case it is desiredto prepare the diamine salt, and warming the reaction mixture attemperatures sufiicient to melt the dicarboxylic acid if it is a solidfor 5 to 15 minutes with or without a catalyst until homogeneousmaterials are obtained.

The dosage of the organic aliphatic dicarboxylic acid glyoxalidine saltrequired for the purpose of the invention is subject to variation but ingeneral very effective results have been obtained by adding relativelyminute amounts of said salt to the hydrocarbon liquid being processed.Amounts of the order of .75 part of the active salt per million parts ofthe hydrocarbon liquid have been effective. Excellent results have alsobeen obtained with 2.5 p.p.m. (parts per million) of the active salt.The lower limit of the amounts used will depend upon the particu laroperation, and in some cases may be as low as 0.5 p.p.m. of active salt.The upper limit of the amount of active salt used will also vary,depending upon the particular operation and especially upon whether theaddition of too large a quantity of the active salt may have some otherdisadvantage or harmful effect which would interfere with subsequentoperations. A harmful effect under some conditions, depending uponwhether water is present and the amounts present, as well as otherfactors, would be the formation of petroleum emulsions. Because of themany difier'ent types of operations where organic liquids are heated toelevated temperatures under conditions where organic deposits areformed, it is impossible to give any specific upper limit of dosagewhich can be adopted in every case but inmost cases the preferred rangeis within the range of 0.5 to 8 p.p.m. of active salt and does notexceed 125 p.p.m. of the active salt. The amount of the active saltwhich is effective to inhibit the formation of organic deposits isreferred to herein as an anti-fouling amount. I

Inasmuch as the active salts are employed in such small amounts and itispreferable to feed them continuously or semi-continuously by means ofa proportioning pump or other suitable device to the particularhydrocarbon liquidbeing processed or to add them in a similar manner tothe apparatus in which the hydrocarbon liquid is being processed, it isdesirable to incorporate the active salt or a mixture of active saltsinto a suitable solvent which crude stock from a desalting process.

4 will be compatible with the organic liquid which is to be processed.

The solvent which is used to dissolve the active effective ingredient isalso subject to some variation depending upon the solubilitycharacteristics of the particular compound employed. lIn some cases,even though the active compound is insoluble in a particular solvent, itwill dis solve in a combination of solvents, for example, the sebacicacid derived by reacting two mols of 1(2-hydroxyethyl)-2-heptadecenylglyoxalidine with one mol of sebacic acid at a temperature of about 133C. for about 5 to 15 minutes is soluble in 100% denatured alcohol,soluble in tlndocene (a petroleum fraction high in aromatic compoundsand naphthas), soluble in 99% isopropanol, insoluble in virgin gas oiland soluble in xylene. This product dissolves satisfactorily in amixture of xylene and naphtha. In general, for most refinery operationsexcellent results have been obtained by dissolving the active salt in ahighly aromatic hydrocarbon solvent.

A concentrate which indicates the best mode for the practice of theinvention has the following composition, hereinafter referred to ascomposition A:

Ingredients: Percent by weight 1-hydroxyethyl-2-heptadecenyl imidazolinesebacate 12.5

Bronoco Hi Sol 87.5

The Bronoco Hi Sol is a highly aromatic hydrocarbon solvent having thefollowing specifications:

ASTM Specification Typical Method Gravity API at 60 F 10l2 13 .8.Specific Gravity at 60 F"-.. 1.000-0.9340 0.9738. gallon Weight, lbs8.328-7.778 8.11.

Corrosion Flash Point, (3.0.

Kauri Butanol Valu Pour Point Mixed Aniline Point D101249T 20 C. Max.133 0 Percent Aromatics D87546T Min 99.2.

Distillation, F DEB-46.

490510.- 520 95% 540 End Point 600 max The following examples illustratethe practical application of the invention in petroleum refineryoperations.

EXAMPLE I This test was conducted in a refinery located in the southernarea of the United States. In the particular part of the refinery withwhich the problem was concerned were two heat exchanging systems whichhandled Prior to being fed into the exchanger systems the crude wasplaced into a storage tank.

Due to the presence of hydrocarbon deposits on the surfaces of theexchangers, operations were materially impeded and the heat transfercapacity of the exchangers was well below that of clean, deposit-freesystem. The exchanger system consisted of three pieces of equipment, thefirst unit comprising one exchanger, and the second being composed oftwo exchangers having a parallel flow connection. The first unit wasconnected to the second so that the crude stock flowed into the firstunit and directly into the second.

, 'The normal operating outlet temperature of the first exchanger aftercleaning was between 235 F. to 245 F., but at the start of the test itwas only 210 F. The secondary unit, when free of deposits, wouldnormally 5 opiate at 300" F. but before starting the test it was runningat 292 F.

Composition A was fed into the crude stock ahead of the storage tank at15 p.p.m. At the ends of the first week the outlet temperature of thefirst exchanger unit had risen to 227 F. At the end of five weeks theentire exchanger system was operating at normal temperatures whichindicated a complete clean-up of the deposits which were fouling theseunits.

After five weeks the units were taken down for cleaning and turn-around.Inspection of the dismantled equipment revealed that the interior sideswere clean except for minor deposits in dead areas. Due to thecleanliness of the system, shutdown time was only days instead of theusual 14 days.

After the unit was placed back in operation the feeding of composition Awas continued and was subsequently reduced to 5 p.p.m. Even at this lowdosage the system remained at high operating temperatures whichindicated an absence of recurrence of deposits.

EXAMPLE II A series of tests were conducted in a largemidwesternrefinery onseveral parts of the processing units where organic depositswere evident.

(A) Toluene extraction tower and stripper This process consisted ofmixing phenol and toluene concentrate in an extractor. The phenolextracted impurities from the toluene; raffinate was subsequentlyremoved. After this step the mixture was sent to a stripper where thetoluene was removed from the phenol by distillation. The remainingphenol was recycled to the extractor for further use.

Deposits in the phenol circuit were causing an excessive amount ofphenol to be lost. These deposits were coke-like in nature and weresloughing off from the high temperature areas of the equipment. Theentire system operated over a wide range of temperatures, viz., 230 F.to 425 F.

The test was conducted over a period of several months with the averagedosages of composition A being at about 25 p.p.m., fed into the phenolmakeup. An additional 5 to 10 p.p.m. was intermittently fed into thephenol circuit based on the toluene production.

At the end of the first two weeks the phenol was heavily laden withdeposits. After this period the phenol was clean and very little wasrequired to go to waste because of excess deposits. The system remainedclean and operated efficiently all during the remainder of the test.

(B) Application to preheater section of fluid catalytic cracking towerThis test was run on a preheater section of fluid catalyti callycracking fractionating tower. Diificulty was encountered due to depositsbuilding up on the heat exchanger equipment. Thecirculation rate of oilthrough the system was 30,000 barrels per day. Due to excessivehydrocarbon deposits in the heat exchangers the operating temperatureswere about 260 F. with the normal operating temperature beingapproximately 370 F.

Treatment was begun using 10 p.p.m. of composition A which was pumpedwith the oil throughout the preheater section. At the end of 70 days theoperating temperatures had reached 360 F. Shortly afterwards theequipment was taken down for cleaning and inspection. The equipment Waspractically free from deposits and the small amounts remaining wereeasily removed.

EXAMPLE III In a large midwestern refinery organic deposits were beingencountered in heat transfer units which were used in conjunction with afurfural extraction system. This system processed the following types oforganic hydrocarbon liquids: intermediate distillates, paraflindistillates, decanted oil, vacuum cylinder stock and decleaning wouldnormally operate for a month or less be:

fore the heat transfer coeflicients would become so low that shutdownwould be necessary. U

At the start of the test composition A was added at 20 p.p.m. Thistreatment was continued for 25 days and the dosage dropped to 15 p.p.m.The dosage was continued at 15 p.p.m. and at the end of 75 days droppedto 5 p.p.m. The unit operated for a total of days before shutdown.

The system was cleaned and put back in operation using a treatment of 10p.p.m. of composition A. The unit ran continuously for five monthswithout any evidence of fouling.

It will be understood that other salts of the type described can beemployed in the practice of the invention. These salts can be addeddirectly to the hydrocarbon liquid being processed. As previouslyindicated, however, the amounts required are so small that it ispreferable to prepare a solution of the active ingredient containingabout 5 to about 15% by weight thereof, the remainder being a suitablesolvent which dissolves the active ingredient and is miscible with themedium to which the solution is to be added.

It will be understood that some variations can be made in thepreparation of the active ingredients and in the procedures employed inusing them. As examples of other long chain aliphatic dicarboxylic acidswhich can be reacted with any of the glyoxalidines previously describedthere may be mentioned the acids known in the trade as VR fatty acid andVR-1 acid. VR fatty acid is an organic carboxy acid material which is avegetable residue resulting from the distillation of soap stock. Thismaterial contains ester bodies and has the following characteristics:

Acid value 45 Saponification value Iodine value 100 Color (Bartlett) l3Viscosity (Zahn G at 75 C.) seconds 15 VR-l acid is a mixture ofpolybasic acids with an average molecular weight of about 1000. It hasan average of slightly less than two carboxylic acid groups permolecule. It is a byproduct from the production of sebacic acid by thecaustic fusion of castor oil, consists principally of polymerizedlinoleic acid, contains dimerized, trimerized and higher polymerizedlinoleic acid, and is a dark amber, rather viscous liquid. A typicalsample of VR-I acid has the following analysis:

Acid number 150 Iodine number 36 Saponification number 172Unsaponifiable matter percent 3.7, 3,5 Moisture content do 0.86

In the practice of the invention it is very often desirable to start thetreatment with the chemicals employed for the purpose of the inventionat a higher dosage, say 20 to 30 p.p.m. of a composition, such ascomposition A,

and then gradually reduce the dosage to the point where foulingiof theapparatus is just eliminated.

The pH of the liquid being treated can vary rather widely. Systems witha pH as low as 0.6 have been suc- 'ping columns, debutan izers,depropanizers, deethanizers,

wherein R is an aliphatic hydrocarbon radical; R, Y and Z are eitherhydrogen or an aliphatic group, it being understood that for the purposeof the present invention R, R, Y and Z are further restricted in themanner previously described. It should also be noted that in thepreferred compounds of the present invention R is composed of carbon andhydrogen atoms, Y and Z are either hydrogen or groups consisting ofcarbon and hydrogen, and R is either hydrogen, a group consisting ofcarbon and hydrogen, a group consisting of carbon, hydrogen andnitrogen, or a group consisting of carbon, hydrogen and oxygen. In otherWords, in the preferred compounds with respect to R the atoms inthegroup are selected from the group consisting of hydrogen, carbon,nitrogen and oxygen.

The invention is hereby claimed as follows:

1. In a process of refining a hydrocarbon liquid at a temperature inexcess of about 225 F., wherein high temperature carbonaceous depositsare formed from said liquid in petroleum refinery apparatus of the typeincluding fractionating towers, stripping columns, debutanizers,depropanizers, deethanizers, heat exchangers, reboilers, and extractors,the method of operation which comprises incorporating with thehydrocarbon liquid supplied to said apparatus an anti-foulnig amount ofa salt of an organic aliphatic 'dicarboxylic acid containing at leastcarbon atoms in a hydrocarbon structure and a glyoxalidine wherein thecarbon atom in the 2-position is linked to a higher aliphatichydrocarbon group containing at least 8 carbon atoms, the carbon atom inthe 4-position is linked to a member from the group consisting ofhydrogen and lower aliphatic hydrocarbon groups containing not more than6 carbon atoms, the carbon atom in the 5-position is linked to a memberfrom the group consisting of hydrogen and lower aliphatic hydrocarbongroups containing not more than 6 carbon atoms, there being at least onehydrogen atom on each of the carbon atoms in the 4- and 5p-ositions, andthe nitrogen atom in the 1-position is linked to a member from the groupconsisting of hydrogen and lower aliphatic groups containing not morethan 6 carbon atoms, said la st named lower aliphatic groups beingcomposed of atoms from the group consisting of hydrogen, carbon,nitrogen and oxygen.

, 2. A process as' defined in claim 1, wherein said hydro carbon liquidis refined at a temperature within the range of.about 225 F. to 800 F.

3. In a process of refining a hydrocarbon liquid at a temperature inexcess of about 225 F., wherein high temperature carbonaceous .depositsare formed from said liquid in petroleum refinery apparatus of the typeincluding fractionating towers, stripping columns, debutanizers,depropanizers, deethanizers', heat exchangers, reboilers', andextractors, the method of operation which comprises incorporating withthe hydrocarbon liquid supplied to said apparatus an anti-fouling amountof a sebacic acid salt of 1-(2-hydroxyethyl)-2-heptadecenylglyoxalidine.

4. In a fluid catalytic process of cracking oil, wherein hightemperature carbonaceous deposits are formed from the oil in thepreheater section of a fluid catalytic cracking fractionating tower, themethod of operation which comprises incorporating with the oil feed tothe preheater section an anti-fouling amount of a salt of an organicaliphatic dicarboxylic acid containing at least 10 carbon atoms in ahydrocarbon structure and a glyoxalidine wherein the carbon atom in the2-position is linked to a higher aliphatic hydrocarbon group containingat least 8 carbon atoms, the carbon atom in the 4-position is linked toa member from the group consisting of hydrogen and lower aliphatichydrocarbon groups containing not more than 6 carbon atoms, the carbonatom in the 5-position is linked to a member from the group consistingof hydrogen and lower aliphatic hydrocarbon groups containing not morethan 6 carbon atoms, there being at least one hydrogen atom on each ofthe carbon atoms in the 4- and 5 -positions, and the nitrogen atom inthe l-position is linked to a member from the group consisting ofhydrogen and lower aliphatic groups containing not more than 6 carbonatoms, said last named lower aliphatic groups being composed of atomsfrom the group consisting of hydrogen, carbon, nitrogen and oxygen.

5. In a fluid catalytic process of cracking oil, wherein hightemperature carbonaceous deposits are formed from the oil in thepreheater section of a fluid catalytic cracking fractionatnig tower, themethod of operation which comprises incorporating with the oil feed tothe preheater section an anti-fouling amount of the diglyoxalidine acidsalt of 1-(2-hydroxyethyl)-2-heptadecenyl glyoxalidine and sebacic acid.

References Cited in the file of this patent UNITED STATES PATENTS2,400,394 De Groote et al May 14, 1946 2,473,577 De Groote et al June21, 1949 2,553,183 Caron May 15, 1951 2,669,546 Zussman et al Feb. 16,1954 2,773,879 Sterlin Dec. 11, 1956

1. IN A PROCESS OF REFINING A HYDROCARBON LIQUID AT A TEMPERATURE INEXCESS OF ABOUT 225* F., WHEREIN HIGH TEMPERATURE CARBONACEOUS DEPOSITSARE FORMED FROM SAID LIQUID IN PETROLEUM REFINERY APPARATUS OF THE TYPEINCLUDING FRACTIONATING TOWERS, STRIPPING COLUMNS, DEBUTANIZERS,DEPROPANIZERS, DEETHANIZERS, HEAT EXCHANGERS, REBOILERS, AND EXTRACTORS,THE METHOD OF OPERATION WHICH COMPRISES INCORPORATING WITH THEHYDROCARBON LIQUID SUPPLIED TO SAID APPARATUS AN ANTI-FOULING AMOUNT OFA SALT OF AN ORGANIC ALIPHATIC DICARBOXYLIC ACID CONTAINING AT LEAST 10CARBON ATOMS IN A HYDROCARBON STRUCTURE AND A GLYOXALIDINE WHEREIN THECARBON ATOM IN THE 2-POSITION IS LINKED TO A HIGHER ALIPHATICHYDROCARBON GROUP CONTAINING AT LEAST 8 CARBON ATOMS, THE CARBON ATOM INTHE 4-POSITION IS LINKED TO A MEMBER FROM THE GROUP CONSISTING OFHYDROGEN AND LOWER ALIPHATIC HYDROCARBON GROUPS CONTAINING NOT MORE THAN6 CARBON ATOMS, THE CARBON ATOM IN THE 5-POSITION IS LINKED TO A MEMBERFROM THE GROUP CONSISTING OF HYDROGEN AND LOWER ALIPHATIC HYDROCARBONGROUPS CONTAINING NOT MORE THAN 6 CARBON ATOMS, THERE BEING AT LEAST ONEHYDROGEN ATOM ON EACH OF THE CARBON ATOMS IN THE 4AND 5-POSITIONS, ANDTHE NITROGEN ATOM IN THE 1-POSITION IS LINKED TO A MEMBER FROM THE GROUPCONSISTING OF HYDROGEN AND LOWER ALIPHATIC GROUPS CONTAINING NOT MORETHAN 6 CARBON ATOMS, SAID LAST NAMED LOWER ALIPHATIC GROUPS BEINGCOMPOSED OF ATOMS FROM THE GROUP CONSISTING OF HYDROGEN, CARBON,NITROGEN AND OXYGEN.